code: def testEmptyFilename(self):
      f = gfile.GFile("", mode="r")
      with self.assertRaises(errors.NotFoundError):
          _ = f.read()
  
imports: import os.path
  from tensorboard import test
  from tensorboard.compat.tensorflow_stub import compat, errors
  from tensorboard.compat.tensorflow_stub.io import gfile
label_desc: Use image node_id 2 for calling the FileIoTest obj's underlying member method code with example usage: obj.testEmptyFilename() without return types